I could be wrong but I thought Brake Pros was the only authorized US importer of AP Racing "street" BBKs?

Nevertheless, I agree that the 368 mm rotor is sufficient in terms of thermal capacity for the e9x M3. I'm running the PFC BBK with a 372 mm rotor and I've never encountered any type of brake issue. If PFC offered a larger rotor I would still use the 372 mm rotor.

Are you purchasing the kit for looks or track use? Several of us use the standard AP kit for street and track and have zero issues. In fact, its more kit then we will probably ever need.

Street and Track, the price difference is not huge, so Im thinking go for the big one. I understand that 368 kit will be far more than I ever need. if there is like 1K different, I will choose 368. Also they use the same caliper CP5555 so only difference is the rotor..

I wonder if that kit was recently released? I'm asking because I just checked the websites of three forum vendors that carry AP and none of them have the 15" (380 mm) kit listed.

Before committing to the larger kit you should check on the price of replacement rotors and pads. If the kit was designed properly it should use a slightly different pad shape (larger inner radius on the pad profile) to accommodate the larger rotor - pad price might not be significantly different but the rotor price will most likely be more expensive.

One other thing you should factor into your decision is whether 18" wheels will clear the 15" rotor.

I wonder if that kit was recently released? I'm asking because I just checked the websites of three forum vendors that carry AP and none of them have the 15" (380 mm) kit listed.

Before committing to the larger kit you should check on the price of replacement rotors and pads. If the kit was designed properly it should use a slightly different pad shape (larger inner radius on the pad profile) to accommodate the larger rotor - pad price might not be significantly different but the rotor price will most likely be more expensive.

One other thing you should factor into your decision is whether 18" wheels will clear the 15" rotor.

I See...So there is no point to go for 378 as it cause too many problems.. Do you know if RS29 will fit AP 368 kit? On there website, I can't find the pad for CP5555.

I'm not familiar with the Pagid line but I do know people use Pagid pads in the AP BBK - it looks like 1538, 1813, 1852 and 1903 pad profiles might fit the CP5555 caliper. I'd check with Richard or other forum vendors to see if the RS29 compound is available and what the correct pad profile is for the AP caliper.

BTW, I incorrectly "cut and paste" the Hawk pad profiles - the 107 and 109 fit the CP5555 caliper.

I'm not familiar with the Pagid line but I do know people use Pagid pads in the AP BBK - it looks like 1538, 1813, 1852 and 1903 pad profiles might fit the CP5555 caliper. I'd check with Richard or other forum vendors to see if the RS29 compound is available and what the correct pad profile is for the AP caliper.

BTW, I incorrectly "cut and paste" the Hawk pad profiles - the 107 and 109 fit the CP5555 caliper.

Thanks a lot~ Just got my Stoptech pad today and will try these on my OEM brake first. Saving money for BBK~~Hope to get a set soon.

I'm not familiar with the Pagid line but I do know people use Pagid pads in the AP BBK - it looks like 1538, 1813, 1852 and 1903 pad profiles might fit the CP5555 caliper. I'd check with Richard or other forum vendors to see if the RS29 compound is available and what the correct pad profile is for the AP caliper.